This invention relates to an editing system and an editing method for editing source video data, and particularly to an editing system and an editing method which enable editing of a higher degree by reading, in real time, a plurality of channels of video data recorded at arbitrary positions on a disk.
In editing at broadcasting stations, magnetic tapes have long been used as recording media for recording video data. Recently, in order to improve the editing efficiency, a non-linear editing machine using a randomly accessible disk medium such as a hard disk (HDD) is introduced. Also, in order to improve the accessibility, it is proposed to use a disk array unit including HDDs connected in an array as a recording medium for carrying out non-linear editing, instead of using a single hard disk.
This disk array unit is a device which includes a plurality of disk units (HDDs) and realizes high-speed reading or writing by operating the disk units in parallel. When data are to be stored in such disk array unit, the data are divided to generate a plurality of divided data and generates error correction data from the plurality of divided data. Then, the plurality of divided data and the error correction data are separately written in the disk unit.
On the contrary, when data are to be taken out from the disk array unit, a plurality of data constituting the data and error correction data are simultaneously read out from the disk unit where the plurality of data and the error correction data are stored, and the original data are constituted by the read out divided data and transmitted without carrying out any processing, if there is no error. At this point, if the data cannot be read out normally for a reason such that a recording area in which the divided data are stored is broken or the like, correct data are restored on the basis of other normally read out subblocks and the error correction data, and are then transmitted.
The disk array unit can be provided with a function such that even when one disk unit is completely broken, the broken data are restored by replacing the broken disk unit with a new disk unit and then using data of the other disk units.
The disk array unit employing error correction data has several different systems. Professor David A. Patterson of U.C. Berkeley classified these systems into five stages and introduced a term of RAID (Redundant Arrays of Inexpensive Disks) levels, for the first time. The contents of the RAID levels are briefly introduced hereinafter.
RAID-1 is a system for doubling data on a disk unit and is also referred to as a mirrored disk. In RAID-1, perfectly the same data are stored in two disk units. In RAID-2 and RAID-3, input data are divided on the bit basis or on the byte basis and are then stored in a plurality of disk units. As error correction data, Hamming codes are used in RAID-2 and parities are used in RAID-3. In RAID-4 and RAID-5, data are interleaved on the sector basis. Parities are stored in the same disk unit in RAID-4, while parities are dispersed into a plurality of disk units in RAID-5.
The system that is most frequently used for the ordinary disk array unit, of these RAID levels, is RAID-3 and RAID-5. FIG. 64 shows the structure of an example of a disk array unit employing the RAID-3 system, and FIG. 65 shows the structure of an example of a disk array unit employing the RAID-5 system.
In the disk array unit of the RAID-3 system shown in FIG. 64, input data are divided into byte units and the respective data divided into byte units are stored in the disk units. Parities as correction data are stored in a predetermined disk unit. In this case, a parity P1-4 with respect to data of numbers 1 to 4 stored in a plurality of disk units and a parity P5-8 with respect to data of numbers 5 to 8 are stored.
In the disk array unit of the RAID-5 system shown in FIG. 65, input data are divided into sector units and these data are interleaved and dispersed into a plurality of disk units. In this case, data A, E and I are stored in the first disk unit, and data B, F and J are stored in the next disk unit. In the subsequent disk unit, data C, G and a parity PI-L with respect to data I to L are stored. Then, data D, K and a parity PE-H with respect to data E to H are stored in the next disk unit, and a parity PA-D with respect to data A to D and data H, L are stored in the last disk unit.
With an HDD used in such disk array unit, in accessing a recording track, the seek time of a head to the track is not so problematical. However, after the head seeks a designated track, the time for the head to wait for rotation of requested data at the designated track position is greatly problematical. This latency time amounts to the time of one rotation of the disk. That is, such problem might not be occur if the requested several frames of data are recorded at physically continuous positions on the disk. However, if the requested several frames of data are recorded at physically random positions, there arises a problem that these several frames of data cannot be read out in real time because of the latency time of the head.
In short, though frames recorded at physically continuous positions can be read out in real time, frame recorded at physically discontinuous positions cannot be read out in real time. Such situations are greatly problematical at broadcasting stations and in the field of broadcast which require real time property in any case. Generally, at broadcasting stations and in the field of broadcast, guarantee of an upper limit of processing time in the worst case is referred to as guarantee of real time property. Particularly in the field of editing, it is very important to enable guarantee of this real time property.
In addition, recently, it is desired that an editing device used at broadcasting stations and in the field of broadcast has a high-degree editing function of processing a plurality of channels of video data in real time. An editing device using the conventional disk array has no such capability as to process a plurality of channels of data in real time, as is known from its inability to compensate real time property even in processing one channel.
In view of the foregoing status of the art, it is an object of the present invention to provide an editing system and an editing method which realize high-degree editing by processing, in real time, a plurality of channels of video data recorded at random positions on a disk.
An editing system according to the present invention includes a data recording/reproducing device for recording/reproducing a plurality of channels of source video data, an editing device for editing the source video data recorded in the recording device, and a computer for controlling the editing device and the data recording/reproducing device. The data recording/reproducing device includes: recording/reproducing means for recording one frame of pixel data of the plurality of channels of source video data onto a plurality of randomly accessible recording media and reproducing a plurality of channels of video streams constituted by desired frames of the plurality of channels of video data stored on the plurality of recording media; and control means for controlling the recording/reproducing means on the basis of a predetermined algorithm for dividing the one frame of pixel data into a plurality of subblocks and transferring the divided subblocks of data to a plurality of different recording media so that the subblocks of data are recorded onto the respective recording media and for recording each subblock data at a position such that a rotational delay time of a head becomes minimum in accessing a desired subblock on the recording medium of each transfer destination. The editing device includes video data processing means for processing, in real time, the plurality of channels of video streams reproduced from the data recording/reproducing device in accordance with an editing indication from the computer so as to generate edited video data.
Also, an editing system according to the present invention includes a data recording/reproducing device for recording/reproducing a plurality of channels of source video data, and a computer for controlling the data recording/reproducing device. The data recording/reproducing device includes: recording/reproducing means for recording one frame of pixel data of the plurality of channels of source video data onto a plurality of randomly accessible recording media and reproducing desired source video data from the plurality of recording media; and control means for controlling the recording/reproducing means by using a first algorithm for dividing the one frame of pixel data into a plurality of subblocks and dispersing the data of the subblocks to a plurality of different recording media, a second algorithm for, in access to a subblock of several frames with respect to each recording medium, scheduling an access order to the subblock of several frames so that a seek distance of a head becomes minimum, and a third algorithm for determining a recording position of each subblock to be recorded on the recording medium so that a rotational delay time of the head becomes minimum in accessing a desired subblock on the recording medium. The computer includes control means for controlling the data recording/reproducing device so as to read out, in real time, a plurality of channels of video streams constituted by desired frames of the plurality of channels of source video data recorded at random positions on the plurality of recording media, from the respective recording media in accordance with operation by an editing operator.
Also, an editing system according to the present invention is adapted for editing a plurality of channels of source video data on the basis of editing information inputted by an operator. The editing system includes: recording means for dividing each frame of pixel data of the plurality of channels of source video data into a plurality of subblocks, allocating divided subblocks so that the respective subblocks are recorded onto a plurality of different disks, and recording the subblocks so that, in each disk, a skew as an angular difference from the center of the disk between a starting point of the data on a track on which the data of the subblock is arranged and a starting point of the data on an adjacent track corresponds to a gap as an angular difference from the center of the disk between a starting point and an end point of one subblock; reproducing means for simultaneously reproducing the plurality of channels of video data by accessing the plurality of subblocks recorded by the recording means; and editing means for processing the plurality of channels of video data reproduced by the reproducing means on the basis of the editing information so as to generate at least one channel of edited video data.
In addition, an editing system according to the present invention is adapted for editing a plurality of channels of source video data on the basis of editing information inputted by an operator. The editing system includes: recording means for dividing each frame of pixel data of the plurality of channels of source video data into a plurality of subblocks, and recording the respective subblocks so that the subblocks are dispersed onto a plurality of different disks and so that, in each disk, a skew as an angular difference from the center of the disk between a starting point of the data on a track on which the data of the subblock is arranged and a starting point of the data on an adjacent track becomes substantially constant; reproducing means for simultaneously reproducing the plurality of channels of video data by accessing the plurality of subblocks recorded by the recording means; and editing means for editing the plurality of channels of video data reproduced by the reproducing means on the basis of the editing information so as to generate at least one channel of video data.
Also, an editing system according to the present invention is adapted for editing a plurality of channels of source video data on the basis of editing information inputted by an operator. The editing system includes: recording means for dividing each frame of pixel data of the plurality of channels of source video data into a plurality of subblocks, and recording the plurality of channels of source video data on the basis of a predetermined recording algorithm for recording the respective subblocks so that the subblocks are dispersed onto a plurality of different disks and so that, in each disk, a rotational delay time of a head becomes minimum in accessing a desired subblock; reproducing means for simultaneously reproducing the plurality of channels of video data by accessing the plurality of subblocks recorded by the recording means on the basis of the predetermined recording algorithm used in recording the source video data; and editing means for editing the plurality of channels of video data reproduced by the reproducing means on the basis of the editing information inputted by input means so as to generate at least one channel of video data.
Also, an editing system according to the present invention is adapted for editing a plurality of channels of source video data on the basis of editing information inputted by an operator. The editing system includes: recording means for dividing each frame of pixel data of the plurality of channels of source video data into a plurality of subblocks, and recording the respective subblocks so that the subblocks of pixel data are dispersed onto a plurality of different disks and so that, in each disk, an angular difference from the center of the disk between a starting point of the data on a track on which the data of the subblock is arranged and a starting point of the data on an adjacent track becomes substantially constant; edited stream generating means for generating an edited stream on the frame basis constituted by desired frames of the plurality of channels of source video data recorded by the recording means; and reproducing means for outputting a video stream corresponding to the edited stream generated by the edited stream generating means, by accessing the plurality of subblocks recorded by the recording means.
In addition, an editing system according to the present invention is adapted for editing a plurality of channels of source video data on the basis of editing information inputted by an operator. The editing system includes: recording means for dividing each frame of pixel data of the plurality of channels of source video data into a plurality of subblocks, and recording the plurality of channels of source video data on the basis of a predetermined recording algorithm for recording the respective subblocks so that the subblocks are dispersed onto a plurality of different disks and so that, in each disk, a rotational delay time of a head becomes minimum in accessing a desired subblock; edited stream generating means for generating an edited stream on the frame basis constituted by desired frames of the plurality of channels of source video data recorded by the recording means; and reproducing means for outputting a video stream corresponding to the edited stream generated by the edited stream generating means, by accessing the plurality of subblocks recorded by the recording means on the basis of the predetermined recording algorithm used in recording the source video data.
Also, an editing system according to the present invention includes a data recording/reproducing device for recording/reproducing a plurality of channels of source video data, and an editing device for editing the source video data recorded in the recording device. The data recording/reproducing device includes: recording means for dividing one frame of data of the source video data into a plurality of subblocks and recording every plurality of subblocks onto a plurality of different disks; reproducing means for reproducing the plurality of subblock data from the plurality of different disks so as to generate one frame of the source video data from the plurality of reproduced subblock data; means for preparing a block map for managing which disk of the plurality of disks is to be used and how a recording area on the disk is to be used in recording the source video data, before starting recording of the source video data; and control means for controlling the recording/reproducing means on the basis of the block map in recording the plurality of subblocks onto the plurality of disks. The editing device includes editing means for controlling the data recording device so as to read out, in real time, desired frames of the source video data recorded at random positions on the plurality of recording media, from the plurality of recording media.
Also, an editing system according to the present invention includes a data recording/reproducing device for recording/reproducing a plurality of channels of source video data, an editing device for editing the source video data recorded in the recording device, and a computer for controlling the editing device and the data recording/reproducing device. The data recording/reproducing device includes: recording/reproducing means for recording one frame of pixel data of the plurality of channels of source video data onto a plurality of randomly accessible recording media, and reproducing a plurality of channels of video streams constituted by desired frames of the plurality of the channels of video data stored on the plurality of recording media; and control means for controlling the recording/reproducing means on the basis of a block map for theoretically managing recording areas on the recording media on the subblock basis so that, in recording a plurality of subblocks generated by dividing the one frame of pixel data onto the respective recording media, each subblock is recorded at a position such that a rotational delay time of a head becomes minimum. The editing device includes video data processing means for processing, in real time, the plurality of channels of video streams reproduced from the data recording/reproducing device in accordance with an editing indication from the computer so as to generate edited video data.
In addition, an editing system according to the present invention is adapted for editing a plurality of channels of source video data recorded on a plurality of recording media. The editing system includes: block map generating means for generating a block map for theoretically formatting recording areas on the recording media so that, in accessing a plurality of subblocks divided from one frame of the source video data, each subblock data is recorded at a position such that a rotational delay time of a head becomes minimum; recording means for recording the plurality of channels of video data onto the recording media on the subblock basis, on the basis of the block map generated by the block map generating means; edit list generating means for generating an edit list on the frame basis constituted by desired frames existing at random positions on the recording media on which the plurality of channels of source video data are recorded; and reproducing means for reproducing a plurality of subblocks corresponding to a frame designated by the edit list from the plurality of recording media on the basis of the block map so that a video stream corresponding to the edit list is generated.
Also, an editing method according to the present invention is adapted for editing a plurality of channels of source video data recorded on a plurality of recording media. The editing method includes the steps of: dividing the one frame of pixel data of the source video data into a plurality of subblocks and transferring the divided subblocks of data to a plurality of different recording media so that the subblocks of data are recorded onto the respective recording media, while recording each subblock data at a position such that a rotational delay time of a head becomes minimum in accessing a desired subblock on the recording medium of each transfer destination; generating an edit list on the frame basis constituted by desired frames existing at random positions on the recording media on which the plurality of channels of source video data are recorded; and repeating processing to reproduce a plurality of subblocks corresponding to a frame designated by the edit list and restore the one frame from the plurality of reproduced subblocks, for each frame designated as the edit list, so as to generate an edited video stream corresponding to the edit list.
Further, an editing method according to the present invention is adapted for editing a plurality of channels of source video data recorded on a plurality of recording media. The editing method includes the steps of: generating a block map for theoretically formatting recording areas on the recording media so that, in accessing a plurality of subblocks divided from one frame of the source video data, each subblock data is recorded at a position such that a rotational delay time of a head becomes minimum; recording the plurality of channels of video data onto the recording media on the subblock basis, on the basis of the block map; generating an edit list on the frame basis constituted by desired frames existing at random positions on the recording media on which the plurality of channels of source video data are recorded; and reproducing a plurality of subblocks corresponding to a frame designated by the edit list from the plurality of recording media on the basis of the block map so that a video stream corresponding to the edit list is generated.